The present invention relates to torsion bars and to vehicle bumpers incorporating same. Implementation of the invention is especially suited for but not limited to pivotally mounted vehicle bumpers designed to remove large animals from the path of a moving vehicle.
The risk of damage caused by collisions with animals such as moose, deer, elk, and other large animals is particularly serious for vehicles such as tractor-trailer and other heavy duty trucks which often move along roads at high speeds. They are unable to stop or navigate quickly within a short distance and collisions with animals are sometimes unavoidable. To address this risk, the result has been a number of front end bumper designs which are variously described as animal protection bumpers, grille guards, moose bumpers, bull bars, elk pushers, roo bars, etc.
Because of the massive forces which can be generated in a collision with a large animal, a suitable animal protection bumper must be strong and is typically quite heavy. In the case of heavy duty tractor-trailer trucks where access to the vehicle engine is often gained by tilting the engine hood forwardly, the bumper is pivotally mounted to the vehicle frame. This enables the bumper to be lowered or pivoted from its normally closed upright position to an open position extending forwardly from the frame. When the bumper is in the open position, the hood can be tilted forwardly without interference from the bumper. The engine and other components carried under the hood can then be serviced by the truck driver or other worker.
Both the lowering of a pivotally mounted bumper from its closed position to its open position and the subsequent raising of the bumper back to its closed position pose a risk of injury to the back. This can be so not only in normal conditions, but particularly so in conditions where the bumper is heavy and the worker's footing is poor as, for example, on icy, snowy or muddy surfaces. By way of example, the weight of the tilting portion of a pivotally mounted bumper for a heavy duty truck may approximate 220 pounds. While the weight distribution may be concentrated towards the pivot axis of the bumper, a worker nevertheless may be required to exert a significant lifting force (e.g. 85 pounds or more) to lower the bumper in a controlled manner to its open position or to raise it back to its closed position.
Therefore, there exists a need for a lift assist that reduces the force which is required to be exerted by a worker when raising or lowering a pivotally mounted vehicle bumper, thereby reducing the risk that a back injury may occur. Preferably, the assist should be robust, should not involve undue mechanical complexity, and should be relatively compact. Compactness is desirable because the available space for installation may be limited.